North American Turbocoupe Organization



'Check Turbo, and ABS' questions
i58829 Offline
Junior Member
#1
Well guys i picked up an 87 5 speed last night, it was driven an hour home, but it has the check turbo light on and the ABS light. Any simple advice or places to look before i have to tear out the turbo and have it checked out? I was thinking along the lines of vacuum lines or something before i got too excited.

And hte brakes function as they should but the light is on.

Should i bother trying to fix this car, or would it be a good one to dump off for a mustang swap? Thanks for your advice in advance, TC...
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Matt S Offline
Posting Freak
#2
The computer doesn't actively monitor the turbo, so I think that is from the overboost solenoid which is on the passenger side in the void between the strut tower and the firewall. I can't recall how it operates if it's not connected electrically. I have bypassed it, leaving the connector on it and have never seen the check turo light come on.

The ABS light just means you have lost ABS function, provided the red brake light is not on then your brakes are operating normally, just without any ABS. Do a search for ABS trouble codes and you will find out how to pull the codes and see why the light is on. Otherwise, again, it is safe to drive.

Most anything in this car can be fixed, and a few minor problems are no reason to dump it and strip it unless there is massive structural rust or there is severe body damage.
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i58829 Offline
Junior Member
#3
Thanks for your help and honest answer, the car does spool up and its as fast as i expected (my father has an 85 auto car, and i've had several SC's) So i'd prefer to keep it. There is only rust on hte rear corners of the rear window, everythign else is solid and i will have pics posted in the general forum later today.

I will check for that sensor, i have a friend w/a 944S turbo and he bought and was told the turbo was bad but it ended being a vacuum issue so he simply replaced all of the lines. It would make sense that the car ran over boost with a bad vacuum line right? I think i read years ago that you could run more boost by simply poking holes (allowing air) into a line that leads to a sensor from the turbo on 87-88's. Thanks again, TC...
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Matt S Offline
Posting Freak
#4
not quite. The wast gate actuator (WGA) is a spring with a vac hose on it. The internal spring is set to about 10lbs. So, without any lines hooked to the turbo, it will only boost to about 10lbs. If you run a tube from the vac tree to the turbo, and boost, your boost holds the WGA closed and, therefore, you overboost. A boost control allows a certain amount of that boost to be bled off, to trick the WGA into staying closed until the desired boost. Most of us use a gillis valve, which allows a precise amount of boost to be given to the WGA holding it closed past 10lbs.

Is the turbo light on all the time or only when you're on the gas? I am assuming you are not having an overboost problem. Do you hear a buzzer come on?

Can't wait to see the pics! And an SC is a whole different beast, and not very comparable just so you know Wink .
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Pete D Offline
Administrator
#5
See this for the brakes:
http://www.turbotbird.com/techinfo/TEVES...%20TCs.htm
Pete Dunham


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JT Offline
Posting Freak
#6
Pete's link above is a good overall overview of the system, but as the article states, it does not troubleshoot the ABS section beyond a few simple checks. It sounds like you have normal braking, indicating the issue is more likely isolated to the ABS.

The ABS light could be on for numerous reasons. Common issues are wheel sensor circuit issues (breakage), failed solenoids, and as the article referenced above suggests, a relay or power failure to the ABS.

It's easy to check the rely to ensure it's receiving and providing power to the ABS system. Beyond that, you will probably need to check for stored trouble codes.

Once you have the stored trouble codes, you can view some of the ABS troubleshooting on my webpage:
http://www.tbirdheritage.com/articles/AB...-Chart.php
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i58829 Offline
Junior Member
#7
Ok here's a few pictures of this thing. Please dont laugh too much, like i said i've been without a bird since i moved to Fl a year and a half ago. Anyway its rough, the nose was backed into in a parking lot and needs a header panel/lights. it hit the core suppor lightly but still blow cold air and holds water. It has like new Kumho tires, and seems pretty tight aside from the shocks/struts bounce a lot in the garage when you push it down. The only rust is behind the rear window, on both corners (pics to come) its a super solid car otherwise, the drivers door is dented pretty badly under the handle, and the paint job is a 20 footer. Yes the whole car looked as bad as the bumper cover when i got it.

Anyway YES the Buzzer came on as i was about to get off I-75 (about 50 minutes into the trip). The turbo light seems to be constant. But the green light by the guage is on when its not making boost so i was using that as an indicator that the system was working correctly.


Now that you've seen some pictures what should i do with it? I have 440.00 invested in the thing and i figured i could have a driver for another 3 or 400 but i dont have any interest in spending over 1000.00 when i can buy a much nicer one for 2500-3000 range. Thanks again, TC...

http://natomessageboard.com/uploads/0000...G_3037.JPG http://natomessageboard.com/uploads/0000...G_3038.JPG http://natomessageboard.com/uploads/0000...G_3039.JPG http://natomessageboard.com/uploads/0000...G_3040.JPG http://natomessageboard.com/uploads/0000...G_3041.JPG
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i58829 Offline
Junior Member
#8
Here's the other pics, anyway that is only rust i found one the car, its very solid on the bottom, and like i said, i'm just not sure what to do with it. If it can be made a reliable driver thats what i would like to do with it.

http://shutter10.pictures.aol.com/data/p...J20280.jpg http://shutter09.pictures.aol.com/data/p...YL0280.jpg http://shutter10.pictures.aol.com/data/p...Pt0280.jpg http://shutter07.pictures.aol.com/data/p...eK0280.jpg
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Matt S Offline
Posting Freak
#9
How many miles are on it? Does it run well otherwise? The ABS is a cheap fix, but you will have to learn how to jumper the connection at the computer to read the abs light blinks in order to get a code. The links will treat you right,and if it's not clear, the abs computer is behind the back seat (drivers side I think?). Get in the trunk and you'll see a brass screw used to hold up the tray. Once you undo the scew the whole thing folds down. I had an ABS light when I bought mine, and it would not return codes so I picked up another ABS computer from someone here for dirt cheap. But there are many things that could cause a code, all pretty much an inexpensive fix.

The green light is indicating if the ride control (PRC) is on firm or not. It has to do with the steering wheel movement, brake pressure, speed and throttle percentage; nothing to do with boost. For instance, the ride control computer puts the struts in firm around 75% throttle (which usually means you have boost heh).

Good news is I see from your pics you have a Gillis adjustable boost valve. That's the brass valve on your VAM in front of the intercooler. The previous owner probably turned it up to, or past, 18lbs; which is when the overboost warning comes on. 15lbs max is stock if you did not have the Gillis. Be forewarned there is a tiny ball bearing and spring in there if you loosen it too much!

Until you have a more reliable gauge, and you are more comfortable with your car, I suggest loosening the outer lock nut, and then screwing out (counter clockwise) the thumb-wheel one-half to one turn to lower boost. The stock "IHI" turbo isn't really efficient above 18lbs anyway. The stock boost gauge in the cluster is not very accurate.

Check your struts to see if they appear to be leaking. These PRC struts seem to last a long time. And the factory ride on this car is very soft. Mine bounced all over the place and so I dropped bank for new/old stock prc shocks/struts, and it didn't change the ride a bit.

These cars can seem picky at first. But they are great commuters when tuned correctly with the right parts, and many members here have hundreds of thousands of miles on their cars. Just let us know what the issues are and we'll help you through it!
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longbedGTs Offline
Senior Member
#10
Hey TC, this is the guy that bought the 350X from you. Looks like a nice project! Good luck with it!
88 TC 5spd~money pit
88 TC 5spd~78K miles
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